We've been using the alarm for three weeks now. The first night I had to wake the BW up by shaking him for a good 10 seconds when the alarm went off. By the end of one week, he was getting up and beating me to the bathroom. (I still had to get up and help him reset the alarm.)
But I was a little frustrated that after two weeks he was still soaking his underwear before he was waking up. Then I had a minor aha moment: I had been clipping the sensor to the outside seam of the leg of his underwear, close to the crotch. In thinking about it, I realized that it was taking a lot of moisture to get that area wet so the alarm wasn't going off until he had pretty much soaked his underwear. I moved the sensor to the front of his underwear and just clipped it directly to the material right on front. Bingo! Within three nights he was waking up quickly enough that his underwear didn't even feel wet.
We had five dry nights last week, two of which he got up in the middle of the night (without the alarm going off) and went to the bathroom. I'm not putting the pull-ups over his underwear anymore as he is now not wetting heavy enough to soak his underwear or his pajamas. I'm not sure how much longer he'll need to wear the alarm but I'm pretty excited about the progress we've made!